1. Field of the Invention
This invention relates to an improved flow through system liquid membrane type electrode used for measuring a specific ion concentration in a liquid sample while the liquid sample is flowing.
2. Description of the Prior Art
FIG. 1 shows an example of a conventional flow through system liquid membrane type electrode, in which a liquid sample flow tube 13 extends through a housing 12 having a cover 11, a communicating bore 14 is formed at the liquid sample flow tube 13, a liquid membrane 15 is connected to the bore 14, an internal electrode 16 is mounted at a predetermined portion of housing 12, and an internal liquid 17 is enclosed in the housing 12. Such a conventional electrode is superior in handling and provides in its flow tube 13 a liquid sample passage D, thereby being advantageous in that its assembly in liquid flow lines is simple and easy.
The smaller the diameter of passage D in the liquid sample flow tube 13, the more suitable the tube 13 for measuring a constituent in a very small sample, and the smaller the outer diameter of the liquid sample flow tube 13, the more compact the electrode as a whole. Hence, a tube smaller in diameter and thickness has hitherto been used as the liquid sample flow tube 13.
Therefore, the conventional electrode is extremely small in an area of junction between the liquid membrane and the communicating bore 14. Moreover, the face of the junction is curved and therefore difficult to join. Also, since the flow tube 13 is small in diameter, it has reduced strength. It is not possible to intensively urge the liquid membrane 15 against the bore so that it is strongly held thereto. As a result, the strength of the junction between liquid membrane 15 and bore 14 is quite low.